Electric power supply system for simplifying the architecture of power and air-conditioning installations

ABSTRACT

A power supply system for uninterruptedly sensitive equipment having a supply interface with a local power line, e.g., of 230V/50 Hz. It has downstream of a high voltage/low voltage transformation station, a direct connection towards at least one Uninterruptable Power Supply (UPS), enabling elimination of the Normal/Standby switch between the local electric network and a replacement source. The UPS, which comprises batteries in parallel and a quick switching device (t&lt;20 ms), automatically ensures the launching (or triggering) of the standby source in case of breakdown of the local electric power supply network. Reciprocally a standby source, which is directly coupled with the UPS batteries, delivers the direct current required for maintaining the charge of said batteries.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an uninterruptible power supply systemintended for sensitive equipment supplied from the public powerdistribution network and required to produce an equivalent voltage inthe event of interruptions or disturbances to the public network.

It is aimed in particular at making it possible to powertelecommunications equipment or computer equipment, or more generallyany equipment for industrial use which accepts neither serviceinterruptions nor brownouts.

2. Description of the Related Art

The equipment commonly encountered in the telecommunications sector isgenerally supplied with DC current at a voltage of 48 volts or with ACcurrent at a voltage of 230 volts. This AC voltage originates from thelocal electricity distribution network which is generally backed up by agenerating set, permanently, depending on the type of system powered.

Power supply chains conventionally comprise three different levels ofconversion:

a primary level with a high voltage/low voltage transformation station,a generating set and a low-voltage distribution board;

a secondary level with rectifiers and accumulator batteries whichconstitute a 48-volt energy source;

a centralized tertiary level with power inverters which deliver an ACvoltage of 230 volts.

The primary level is generally situated within technical premises(cellar, basement, ancillary premises) which are remote from theequipment rooms which comprise the secondary level and the tertiarylevel.

Accumulator batteries have been made reliable through the use ofleakproof batteries and computer monitoring facilities which scan thefailure modes.

The architecture of the present generation of power supply chains mustevolve on account of the alterations encountered in the equipment:

the rising proportion of equipment exhibiting a 230 V/50 Hz power supplyinterface, to the detriment of the 48 V interface,

the considerable reduction in the power consumed by telecommunicationsequipment,

the ability of equipment to operate at extreme temperatures with noimpact on their lifetime and on the quality of service.

These evolutionary factors lead to the favouring of second-generationpower supply systems based on an architecture which includesUninterruptible Power Supplies (UPS) to the detriment of 48 V sourcesand inverters.

French Patent 2 693 052 or the document CHIGOLET JC et Al. disclosepower supply chains of the new generation whose operating principleexploits a technique of optimized and distributed energy. This techniquemakes it possible:

to separate the power supply and energy storage functions in the UPS ofOFF LINE type so as to optimize the management of the batteries andthereby to increase their lifetime,

to improve the energy efficiency of the uninterruptible power supplychain as compared with the present-day technical solutions,

to relocate the AC distribution racks to the technical premises ratherthan in the equipment rooms, which will make it possible to eliminateoperator constraints:

weight of the cabinet-mounted batteries, effects of high temperature onthe lifetime of 5 the batteries when the production of cold isdeliberately reduced so as to achieve energy savings,

risks of disturbances through electromagnetic radiation related to thecloseness of the UPSs, maintaining of raised floors so as to conceal thelarge cross-section cables required for distribution at 48 V.

The British document GB-A-2 184 903 also discloses an installation whichuninterruptibly supplies power to sensitive equipment exhibiting acurrent-supply interface. This installation comprises batteries and afast switching device making it possible automatically to trigger areplacement source, the said replacement source ensuring that the chargeof the said batteries is maintained by way of a rectifier.

The document EP 0 734 113 describes a system which exploits the inertiaof the rotor, which continues to rotate even when the main power supplyis cut, to trigger another generator which will cater for the electricalprovision. Moreover, the presence is noted in this document of aNormal/Backup changeover switch (or LCI—Load Commutated Inverter) whichswitches over the networks, in the event of a failure.

These technical solutions of the new generation will enable theequipment to be powered at 230 V by UPSs which are located remotely intechnical premises, with small cross-section distribution cables whichcan be trunked over decking or duckboards.

The drawbacks of the solutions known hitherto lie, on the one handmainly in the recourse to backup sources which call upon generatingsets, driven by diesel sets having non-negligible operationalconstraints:

environmental pollution (operating noise, vibrations, exhaust gases)

mediocre performance and dimensioning constraints,

high operational cost (preheating, servicing, etc.), and on the otherhand in the use of a low-voltage board and of a Normal/Backup changeoverswitch (changeover switch and shunting device).

Moreover, the generating sets require a startup system dedicated to thereplacement source (battery, rectifier, charger).

The present generation of solutions additionally requires ancillarybackup devices for maintaining the connected equipment operational(backup for the air-conditioning, inverters protecting the computersagainst brownouts and disturbances, etc.)

BRIEF SUMMARY OF THE INVENTION

The present invention aims to alleviate these drawbacks by proposing anUninterruptible Power Supply system which does not include any functionof Normal/Backup swapover between the local electrical network and thereplacement source, this replacement source moreover beingenvironmentally friendly.

To this end, system which uninterruptibly supplies power to sensitiveequipment exhibiting an AC current supply interface, is characterized inthat it comprises downstream of a high/low voltage transformationstation, a direct link to at least one uninterruptible power supply(UPS) unit which comprises batteries in parallel and a fast switchingdevice, making it possible automatically to ensure the triggering or thestarting up of a replacement source (RS) in the event of a failure ofthe local electricity network, the said replacement source being coupledto the said batteries of the (UPS) and delivering a DC current requiredfor maintaining the charge of the said batteries, thereby making itpossible to dispense with the Normal/Backup changeover switch of thelow-voltage distribution situated upstream of the (UPS).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other characteristics and advantages of the present invention willemerge from the description given below, with reference to the appendeddrawings which illustrate an exemplary embodiment thereof devoid of anylimiting character. In the figures:

FIG. 1 is a schematic view of a conventional first-generation powersupply chain;

FIG. 2 is a schematic view of a new-generation power supply chaincomprising an Uninterruptible distributed-storage Power Supply;

FIG. 3 is a schematic view of a power supply chain forming the subjectof the invention, comprising a Simplified Architecture Designed for theTechnical and Energy Environment.

DETAILED DESCRIPTION OF THE INVENTION

Represented in FIG. 1 by HT/LT is the 25 high/low voltage transformationstation, by GE the generating set responsible for supplying theinstallation with electrical power in the event of a failure of thelocal electrical network, by LVB N/B the technical rack whichfurthermore includes the low-voltage board and the Normal/Backupswapover device, by REC BIE the rectifiers and the accumulatorbatteries, and by INV the power inverters.

Represented in FIG. 2, over and above FIG. 1, by UPS is anuninterruptible power supply comprising a fast-switching breakerallowing outage-free powering of the equipment, placed downstream, fromthe UPS.

Illustrated in FIG. 3 by RS are the replacement sources making itpossible to recharge the accumulator batteries included within the UPS,these latter also being able to bring the replacement sources intooperation.

Represented by a thin chain-dotted line in FIGS. 1, 2 and 3 is theseparation between the technical premises and the equipment room.

According to a preferred embodiment of the power supply system, anUninterruptible Power Supply is connected downstream of a HT/LTtransformation station of a local electrical network, which is bydefinition not backed up.

The medium-duration energy storage circuit of the UPS is associated witha standard conversion device (inverter) placed on standby, which isresponsible for providing an outage-free AC voltage while awaitingstart-up or the provision of energy to the UPS by the replacementsources.

Thus, if the local electrical network is cut of f or exhibits faults orirregularities for a period of a few minutes, no disturbance will beobserved in the operation of the sensitive equipment so long as itaccepts brownouts of less than 20 ms duration.

Conventionally, a UPS of _OFF-LINE_type has a medium-duration energyreserve and comprises a separation transformer, the objective of whichis a high degree of safety of personnel and the carrying out of a firstfiltering of network glitches. Batteries having a voltage of between inparticular 200 and 400 V ensure self-sustaining operation in the standbystate, by virtue of a fast switch for toggling between the network andthe inverter.

Downstream of the UPS, that is to say at the output of the inverter,there is provision to locate a distribution box, to which are connectedsupply lines which it is desired to make safe, and thus into which areplugged the equipment for industrial use which accept neither serviceinterruptions, nor brownouts of greater than 20 ms (telephone andcomputer equipment, air-conditioning, backup lighting etc.).

According to another characteristic of the invention, a DC currentsource originating from a replacement source RS is coupled with thebatteries constituting the store of energy in the UPS. This DC currentsource maintains the charge of the batteries of the UPS in the event ofa failure of the local electrical network.

This so-called _direct_wiring makes it possible to dispense with theNormal/Backup swapover function and also with the low-voltage board LVBwhich exists in the known solutions of the prior art (first and secondgenerations).

According to another aspect of the invention, the replacement sourcesIRS consist in particular of turbo generators or of fuel cells, whichare started up, in the event of a fault encountered in the supply of thelocal electrical network, by means of a current originating from thebatteries of the UPS. Indeed, these batteries have high power and thetriggering or the starting up of the replacement sources IRS is effectedprogressively, requiring only a low intensity on start-up.

If a turbo generator is used as replacement source, the alternator whichis preferably of small diameter, is spun at a high and constant speed ofrotation, through the use of a turbine, and possibly at the same speedof rotation as the turbine, in such a way as to deliver a high-frequencycurrent, which is transformed into DC current after rectification andfiltering, and which is able to recharge the batteries of the UPS atconstant voltage.

If a fuel cell is used as replacement source, the latter comprises acertain number of elementary cells, mounted in series, which deliver aDC current at a high voltage which is directly useable for rechargingthe batteries built into the UPS at constant voltage.

Regardless of the type of replacement source IRS, the batteries areinstantaneously invoked by the inverter of the UPS in the event of afailure of the local electrical network, in such a way as to ensure asecure power supply for the equipment connected to the UPS.

The batteries of the UPS can also be recharged 5 by way of an alternatorrotated by a low-speed generating set; nevertheless this technicalsolution involves extra cost in view of the adaptation required for theproduction of a DC current.

The invention described above offers multiple advantages in regard, onthe one hand to the reduction in hardware investment costs (eliminationof the low-voltage board LVB, of the Normal/Backup changeover switch,elimination of the system for starting up the replacement source,elimination of the air-conditioning backup device, elimination of theinverters protecting the computer network, and on the other hand to theimprovement in the operational conditions, disappearance of currentoutages during Normal/Backup switchover, constant quality of the securesupply, self-sustaining operation which is homogeneous from the thermaland electrical standpoint, improvement in start-up reliability of thereplacement sources through optimized management of the batteries builtinto the UPS. Moreover, this entire power supply system is built intothe ancillary premises of an installation away from the operationalpremises, by virtue of the distributed voltage which ranges from 48 V(for DC) to 230 V (for AC). This arrangement makes it possible to reducethe length of the link between the UPS and the start-up system.

It is of course obvious that the present invention is not limited to theexemplary embodiments described and represented hereinabove, but that itencompasses all variants thereof.

What is claimed is:
 1. System which uninterruptibly supplies power tosensitive equipment exhibiting a current supply interface, comprisingdownstream of a high/low voltage transformation station (HT/LT), adirect link to at least one uninterruptible power supply unit (UPS)which comprises batteries in parallel and a fast switching device,making it possible automatically to ensure the triggering or thestarting up of a replacement source (RS) in the event of a failure ofthe local electricity network, said replacement source (RS) beingcoupled to said batteries of the supply unit (UPS) and delivering a DCcurrent required for maintaining the charge of said batteries, therebymaking it possible to dispense with the Normal/Backup changeover switch.2. Uninterruptible power supply system according to claim 1, wherein thereplacement source (RS) comprises a fuel cell, delivering the DCcurrent.
 3. Uninterruptible power supply system according to claim 1,wherein the replacement source (RS) comprises a turbogenerator,delivering the DC current.
 4. Uninterruptible power supply systemaccording to claim 1, wherein the replacement source (RS) comprises agenerator or an alternator rotated by a low-speed generating set,adapted for delivering DC current.
 5. Uninterruptible power supplysystem according to any one of the preceding claims 1-3, wherein thepower supplies which one wishes to make secure relate in particular toair-conditioning, backup lighting, the power supply of the replacementsource (RS) and telephone and computer equipment.
 6. Uninterruptiblepower supply system according to claim 4, characterized in that it isbuilt into an ancillary premises of an installation thus equipped so asto make it possible to reduce the length of the link between the supplyunit (UPS) and a start-up system.